The present invention generally relates to a method of manufacturing a semiconductor device, and more particularly, to a method for using a silicon on insulator (SOI) semiconductor wafer for manufacturing devices having very thin and fragile substrates.
Semiconductor wafer fabrication generally refers to the process of making integrated circuits on silicon wafers. A typical semiconductor wafer is generally circular in plan view and has a diameter on the order of 25-300 millimeters (mm). Individual electronic circuits or devices are formed across at least one surface of the wafer and then the wafer is typically cut (sawed or diced) into a plurality of individual “dies” for packaging into individual integrated circuits (ICs).
Silicon on insulator (SOI) semiconductors, dielectric isolation (DI) semiconductors and bonded wafer semiconductor devices are generally known in the art. For example, basic known processes to bond semiconductor wafers include forming a layer of silicon dioxide on one silicon wafer, sometimes referred to as the “handle wafer” and placing the other wafer on the silicon dioxide and annealing (i.e., generally heating to and holding at a suitable temperature and then cooling at a suitable rate) the stacked wafers to form a bonded wafer semiconductor device having a buried oxide layer. Other methods of forming SOI semiconductor wafers are also known.
A handle wafer can be used to handle a semiconductor wafer during processing. Typically the device layer of semiconductor material is processed, e.g., trenched, implanted, doped, polished or the like, and is therefore moved from process to process. As device layers shrink or become more thin, they also become more fragile and hard to handle during processing.
Wafer sawing or dicing is a processing step that actually cuts the wafer into individual dies for assembly into IC packages. The wafer saw process typically includes mounting the wafer to a frame, cutting the wafer through its thickness according to the programmed die dimensions using a diamond cutting wheel rotating at a very high speed and cleaning the wafer using high pressure water spray. Alternately, wafers can be diced using a water-jet-guided laser. Improper wafer sawing can result in cracks in the wafers which is often referred to as die cracking. Even proper sawing may lead to die cracking in very thin wafers.
It is desirable to provide a technique to allow stable processing of thin and fragile semiconductor substrates. It is desirable to provide a method of manufacturing such thin semiconductor devices using SOI wafers and a deep trench etch. It is also desirable to provide a technique to manufacture larger diameter wafers with a lower level of breakage and/or die cracking.